I've had a request for a photo of a stock unit with mostly gray hair. Here's a photo of a Super Fine Swiss lace stock unit. It's 20% color #1b and 80% gray.
It's a stock unit. Medium density (65%) and human gray. FYI, synthetic gray cannot be used in percentages greater than 30%---that much synthetic hair just does not blend well with real human hair. In amounts less than 30% synthetic hair blends just fine with real human hair.
Regards,
John